1. Lecture 13 Dendrites: Function Rachel A. Kaplan and Elbert Heng 4.1.14

2. Announcements We hope you had a nice break! We will have your exams graded to hand back to you by Thursday Please fill out the survey if you already haven’t

3. An Overview “Dendrites integrate subthreshold synaptic inputs and ultimately control neuronal output” Again, central thesis of neuroscience: neurons transmit information – Input is input to dendrites – Dendrites by their nature change input – Changed inputs are integrated by soma – Soma then outputs output Information is thus transmitted

4. Input to dendrite that reaches soma can be affected by... We’ve seen before: LEAKY CABLE STRUCTURE – Length constant – Time constant Both of these have implications for summation of inputs Resultantly: – Relative timing of inputs matters (this lecture doesn’t get into this) – Distance of synapse from soma matters

5. Solutions to the Leaky Cable Problem Passive properties of dendrites – Morphology adjustments – Large dendrites – Larger EPSPs Active properties of dendrites – Spiking!

6. PASSIVE PROPERTIES

7. Morphology The more resistance a dendrite provides, the more of the current and change in voltage will be transmitted farther. – (we learned this with length/time constant) As a result, it’s been shown that larger dendrites are thicker – But diameter can only increase by so much...

8. Larger Distal Inputs Distal synapses do produce larger distal inputs! – Greater magnitude so decay over distance does not as greatly affect input This is due to greater glutamate receptor density

9. ACTIVE PROPERTIES